This exploratory study (R21) addresses HIV risk among male, migrant Latino day laborers in suburban Maryland, just outside Washington, DC. Day laborers seek work in informal markets (typically outdoors) or, less commonly, through temporary-work staffing agencies. There is negligible extant research on this population, but there is evidence to suggest that Latino day laborers are at risk for contracting HIV. This study involves a partnership between George Washington University and Casa de Maryland, a community-based organization serving Latino day laborers. It is innovative because it investigates individual characteristics and their impact on sexual risk behavior within the social and structural context encountered by day laborers. The study has public health significance because it will result in knowledge concerning sexual risk and barriers to HIV testing in an underserved and vulnerable group characterized by delayed testing and late entry to care. The specific aims are: 1) To describe individual, social, and structural conditions that affect male, migrant, Latino day laborers in the inner Maryland suburbs of Washington, DC;and to test the impact of demographic characteristics, cultural characteristics, experiences of discrimination, and living situation on sexual risk behavior;2) To examine ways in which conditions arising from social and structural factors influence binge drinking and loneliness, and to explore the impact of binge drinking and loneliness on sexual risk behavior;and 3) To examine attitudes toward and barriers to HIV testing in the target population. Qualitative and quantitative methods will be used. Key informant interviews (N=10), in-depth interviews with day laborers (N=10) and female sex workers who serve them (N=5), and focus groups with day laborers (2 groups with 8 to 10 participants;N=20) will provide detailed descriptions of the social and structural conditions of day laborers'lives and will illuminate the multiple factors shaping risk behavior and barriers to HIV testing. Patterns of use of female commercial sex workers and associated sexual risks will also be investigated. A quantitative survey, administered with Audio-CASI (N=20 for pilot;N=175 for full sample), will be used to test hypotheses concerning 1) the impact on sexual risk behavior of individual characteristics that may arise from social and structural conditions;2) the role of loneliness and binge drinking as mediators of the effects of such characteristics;and 3) the importance of different types of barriers to HIV testing. The resulting knowledge will be useful for the design of HIV prevention efforts and future research. It will identify relevant conditions that could be addressed at multiple levels, including through interventions aimed at individuals (e.g., to change people's attitudes about HIV testing), social programs affecting the community (e.g., to create opportunities to build bonds and thereby lessen social isolation and loneliness), and policies enacted by government (e.g., to improve access to health services). PUBLIC HEALTH RELEVANCE: This exploratory study will have public health significance because it will examine individual HIV risk behavior of male, migrant Latino day laborers within the social and structural contexts of their lives. Moreover, it will result in knowledge concerning barriers to HIV testing in an underserved and vulnerable group characterized by delayed testing and late entry to care. This study will identify relevant conditions that could be addressed at multiple levels, e.g., through interventions aimed at individuals (e.g., to change attitudes about HIV testing), social programs affecting the community (e.g., to create opportunities to build bonds and thereby lessen isolation and loneliness), and policies enacted by government (e.g., to improve access to health services).